Cytomegalovirus (CMV) is a human herpesvirus responsible for considerable morbidity and mortality in newborns, AIDS patients, transplant recipients and other immunocompromised patients. The regulation of CMV gene expression is a complex task requiring the sequential and coordinate expression of approximately one hundred genes. Following transcriptional activation, posttranscriptional events play a prominent role in controlling the kinetics and extent of CMV gene expression. The primary goal of this research is to elucidate translational and other posttranscriptional mechanisms which control the expression of CMV genes. Transient assays and in vitro translation assays will be used to identify new cis-acting signals which influence the expression of the CMV genes focusing on the DNA polymerase gene, pp150 and the major 2.7kb beta gene. The specific posttranscriptional level at which each signal operates will be determined by subcellular localization of transcripts using hybridization analyses. The regulatory role of upstream AUG codons, apparently common elements of CMV genes which are known to be translational control signals in several systems, will be ascertained by deletion and site specific mutation analyses. Since it is likely that these cis-acting signals are targets of cellular or viral trans-acting factors, the role of trans-acting factors in the observed translational regulation will be investigated using cotransfection and in vitro translation assays. The 2.7kb beta gene encodes the most abundant viral transcript at early times of infection yet its gene product(s) is unknown. Because of the likely importance of this gene in CMV biology and because it contains translational control signals, the gene product (s) will be identified using polyclonal antipeptide antisera. Finally, past studies of CMV gene regulation have concentrated on productive infections in cell culture. Ultimately, dissection of the regulation of CMV gene expression in naturally occurring infections whether productive, latent or abortive will be necessary to understand the biology of the virus and to formulate strategies aimed at controlling infection. CMV-regulated gene expression in nonpermissive cells will be assayed to determine the role of translational controls in limiting the host range of CMV. In situ hybridization and antigen detection techniques will be used to study CMV gene expression during naturally occurring infections in human tissues.